Kidney Diseases Associated With Inflammatory Bowel Disease: Impact of Chronic Histologic Damage, Treatments, and Outcomes.

Introduction: Kidney disease is a well-known extraintestinal manifestation (EIM) associated with inflammatory bowel disease (IBD), with a variety of underlying etiologies. However, little is known about the overall outcomes and predictors. Methods: This is a retrospective, observational cohort study. Patients with IBD in whom a native kidney biopsy was performed at Mayo Clinic (Rochester, MN) between 1994 and 2022, were included. Demographic, clinical, and histologic characteristics of prognostic interest were collected. The main outcomes were kidney failure, disease remission, kidney function changes at last follow-up, and death. Results: From a total cohort of 318 patients, we selected a study group of 111 patients followed-up with at our institution (45 ulcerative colitis [UC] and 66 Crohn's disease [CD]), with a mean age of 48 ± 17 years (40% females). IgA nephropathy (IgAN), chronic interstitial nephritis (CIN), and acute interstitial nephritis (AIN) were the most common diagnoses (22%, 19%, 13%, respectively). Median estimated glomerular filtration rate (eGFR) at presentation was 30 ml/min per 1.73 m2 (interquartile range [IQR]: 17-54) and urinary protein-to-creatinine ratio [UPCR] 0.8 g/g (0.3-3.4), without differences between IBD types. During a median follow-up of 59 months (12-109), 29 patients (26%) reached kidney failure. By multivariable analysis, the main predictors of kidney failure were age (hazard ratio [HR]: 1.04; P = 0.002), baseline eGFR (HR: 0.94; P = 0.003) and histologic chronicity score (HR: 4.01; P < 0.001). Therapeutic management varied according to underlying etiology. Global survival (kidney failure + death) was significantly better in patients who achieved complete or partial remission, or stabilization or improvement of kidney function. Conclusion: One-fourth of patients with IBD with kidney disease may reach kidney failure, and the main determinants of this outcome is age, baseline eGFR, and degree of chronicity in kidney biopsy.

Tirzepatide and prevention of chronic kidney disease.

Tirzepatide is a twincretin recently approved to improve glycemic control in type 2 diabetes mellitus (T2DM). More specifically, tirzepatide is an agonist of both the glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide-1 (GLP1) receptors. In recent clinical trials in persons with obesity or overweight with associated conditions, tirzepatide decreased body weight and other cardiorenal risk factors (blood pressure, low-density lipoprotein cholesterol, glycated hemoglobin and albuminuria). Moreover, in a post hoc analysis of the SURPASS-4 randomized clinical trial, tirzepatide decreased albuminuria and total estimated glomerular filtration rate (eGFR) slopes and nearly halved the risk of a pre-specified composite kidney endpoint (eGFR decline ≥40%, renal death, kidney failure or new-onset macroalbuminuria) in participants with T2DM and high cardiovascular risk when compared with insulin glargine. Similar to other kidney-protective drugs, tirzepatide, alone or combined with sodium-glucose co-transporter 2 inhibitors, caused an early dip in eGFR. Moreover, tirzepatide also decreased eGFR slopes in participants with eGFR >60 mL/min/1.73 m2 or with normoalbuminuria. We now review the potential kidney health implications of tirzepatide, addressing its structure and function, relationship to current GLP1 receptor agonists, impact of recent results for the treatment and prevention of kidney disease, and expectations for the future.